Such ball-and-socket joints, in which the joint ball is fitted in a joint socket made of wear-resistant plastic with limited elasticity, and is inserted with the joint socket into a housing, are described in West German Auslegeschrift No. 15,75,539. Instead of the slots in the joint socket, which are described in this publication, grooves provided on the inner wall of the joint socket are known from West German Auslegeschrift No. 10,14,441 and West German Auslegeschrift No. 24,56,571. Lubricant greases, which are fed to the bearing areas of the joint via the slots or via the lubricant grooves of the joint socket, are used to bring about a general reduction of friction and wear in the bearing.
It has been found in the course of many years of use of these ball-and-socket joints, which possess good articulation properties per se, that thickened areas are formed in the socket wall. These thickened areas form at the transition to the slot or to the lubricant groove, due to manufacturing reasons, during the manufacture of injection molds for the joint sockets and due to the shrinkage of the plastic during the injection molding of the joint shells. In the assembled state of the ball-and-socket joint, these thickened areas lead to partially increased surface pressures, which pressures cause the grease to be stripped off during the movement of the joint ball in the joint socket. The bearing zones of the ball-and-socket joint are thus deprived of grease, so that the opposite of the intended effect is achieved. This is prevented in a prior-art design according to West German Design Patent No. 74,24,445 by the joint having a very thin joint shell without lubricant grooves in the bearing surface and being supported against the housing by ribs or the like arranged on the outside of the joint shell.
Another problem lies in the fact that increasingly exacting requirements have been imposed on the components, especially ball-and-socket joints, in terms of the maximum permissible loads, minimumization of the friction torque, zero clearance, low elasticity, and high temperature resistance in the course of the further development of components for motor vehicles and the technical as well as economic optimization of such components.